1. Field of the Invention
The present invention relates to an image forming apparatus connectable to a peripheral unit provided with a paper conveyance section, and an operation method for use in the image forming apparatus.
2. Description of the Related Art
In recent image forming apparatuses such as digital copy machines, peripheral units, such as a paper feed unit of a large capacity, a paper discharge unit for distributing discharged paper sheets, etc., are provided as optional units that can be mounted optionally. On the other hand, digital copy machine main units are classified into different types that have the same structure and different copying speeds (e.g. 55, 65, 80 sheets/min.).
Therefore, when a peripheral unit, such as a paper feed unit or discharge unit having a paper conveyance function, is connected to digital copy machine main units of different copying speeds, it is necessary to adjust the speed of a driving system, incorporated in the peripheral unit, in accordance with the conveyance speed of each main unit.
In other words, it is necessary to prepare a peripheral unit corresponding to the copying speed of each main unit. This may involve errors in management or mounting operations. Further, if a plurality of peripheral units are modified as they are common, to avoid such a matter, so that they can be connected to any one of the main units, it is necessary to adjust the driving speed of the motor of the peripheral unit, i.e. the paper conveyance speed of the peripheral units, to the highest paper conveyance speed of each main unit. In this case, if the conveyance speed of the main unit to be connected to the peripheral unit is slow, the current for driving, for example, the driving motor of the peripheral unit is too large, whereby the power consumption becomes large and the motor may generate big noise.
A motor driving circuit may be employed in the main unit for optimizing the motor driving current. In this case, however, the main unit must contain the motor driving circuit even when no peripheral unit is connected, which results in an increase in cost.
It is an object of the invention to provide an image forming apparatus, in which even if peripheral units of a single paper conveyance speed are connected to the main unit of the apparatus of a variable paper conveyance speed, the power consumption and motor noise can be reduced, since the conveyance speed of the peripheral units and the upper limit of the current used to drive the motor of the peripheral units are set at the main unit side, and also provide an operation method for use in the apparatus.
According to an aspect of the invention, there is provided an image forming apparatus having a main unit including a printing section which executes printing on a paper sheet, and also having a peripheral unit connected to the main unit. This apparatus comprises: a first conveyance section provided in the main unit and used to convey a paper sheet at a set speed; a second conveyance section provided in the peripheral unit and used to convey a paper sheet at a predetermined speed; a storage which stores setting data on a conveyance speed of the second conveyance section, and an upper limit of a current used to drive a motor in the second conveyance section, the conveyance speed of the second conveyance section and the upper limit being varied in accordance with a type of the main unit, the conveyance speed of the second conveyance section being stored in association with the upper limit; a type setting section which sets the type of the main unit; and a setting section which sets, in accordance with the set type, the conveyance speed of the second conveyance section and the upper limit of the current used to drive the motor in the second conveyance section.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.